By default any nested component will be automatically attached to its parent component according to their parent-child relationship. Here Guard is automatically attached to its parent (Application here) as its root. Adding attribute autoAttach:false can disable this feature.

In Restlet, an attaching operation (on Router.attach) returns an instance of Route. It might be needed to do some post processing on a route. Attribute postAttach which refers a closure is used to support this.